DESCRIPTION: The goal of this application is to synthesize a nanostructured thermoset for use as a Dental restorative. A nanostructured thermoset will have superior properties to conventional composite materials. Bone and teeth are examples of nanostructured composites and our goal is to take advantage and mimic the nanoscale control found in these materials. Nanoscale building blocks will be synthesized and used to form nanostructured thermosets with superior mechanical properties. Simple modifications to the structure of the building blocks will affect the bulk properties of the thermosets. The molecular building blocks can act as a platform to develop a broad range of functional materials. Liquid crystalline organic-inorganic hybrids based on polyhedral silsesquioxane (POSS) will be used as the building blocks. POSS contains both organic and inorganic components so controlled composite structures can be formulated without the inherent problems of mixing. The liquid crystalline phase will impart nanoscale order to the liquid crystalline building blocks. To retain the nanoscale order, the liquid crystalline POSS will be made visible light curable with the addition of methacrylate groups. Irradiation with visible light will form a thermoset that will retain the nanoscale order of the liquid crystalline phase. The thermosets will be evaluated by X-ray diffraction and TEM to confirm their nanostructure. Conventional evaluations for clinical performance such as flexural strength, compressive strength, shrinkage and wear will be performed. This application represents a new methodology in the design of dental restoratives.